convert a byte array to string

Question

My Scala code received a binary from byte stream,it looks like [61 62 63 64].The content is "abcd". I use toString to convert it p, but failed. How do I print it as string ?

Solution 1

You could convert the byte array to a char array, and then construct a string from that

scala> val bytes = Array[Byte]('a','b','c','d')
bytes: Array[Byte] = Array(97, 98, 99, 100)

scala> (bytes.map(_.toChar)).mkString 
res10: String = abcd

scala> 

Solution 2

You can always convert the byte array to a string if you know its charset,

val str = new String(bytes, StandardCharsets.UTF_8)

And the default Charset would used if you don't specify any.

Comments

[Quentin]

Try to parse each number as a char and concate them to have a string

[Sameera.San]

Converting byte array to string

[Alexander Azarov]

Possible duplicate of Byte array to String and back.. issues with -127

[BAE]

Curious which method is better, (bytes.map(_.toChar)).mkString or new String(bytes)?

[Micheal Hill]

@BAE this is perhaps a bit late for you; but the two could potentially produce different results. UTF-8 is a variable width encoding, so a single character could be encoded with a single byte or multiple. UTF-8 encodes ASCII characters in the same way (eg. A is represented by 65 in both) but most (maybe all?) other characters with multiple bytes. In short; they're the same if your string contains only ASCII characters but otherwise will produce different results.

[cms]

@MichealHill assuming that the stream is a UTF-8 stream is a fairly reasonable for text payloads nowadays. The original question asked to print out a 'binary' byte stream, this particular case does not imply a string encoding. This is why it's best to provide an encoding when you're transmitting strings. (You can use frequency analysis to infer a probable string encoding if you have a text stream with no indicated encoding)

[Murray Todd Williams]

As @michael-hill already mentioned in a comment below, this can cause problems because it assumes you're working in ASCII and not UTF-8 or some other character encoding. If you were to try to convert the following (proper) UTF-8 byte array to a String... val msg = Array[Byte](-17, -69, -65, 72, 101, 108, 108, 111) (msg.map(_.toChar)).mkString You would get something that looked very weird and not the expected "Hello" that you would get from this: new String(msg)

[jwvh]

Two things: 1-I don't see what all the type conversions are for. Why not just bytes.mkString(" ")? and 2-This answer is out of place. It doesn't answer the question asked.

[Jacob Wang]

As @cms said, this is really bad advice. Please don't do this. This can lead to silent data corruption and other hard to track down bugs

[tgrrr]

println("🍕".getBytes(StandardCharsets.UTF_8).length) > 4